Crank-shaft and the corresponding crank-case



June 25, 1957 J. L. GRATZMULLER 2,796,769

CRANK-SHAFT AND THE CORRESPONDING CRANK-CASE Filed Feb. 3, 1954 sShets-Sheet 1 Fig.

Invenhr Affor ny} June 25, 1957 J. GRATZMULLER 2,796,769

CRANK-SHAFT AND THE CORRESPONDING CRANK-CASE Filed Feb. 3, l954 5Sheets-Sheet 2 FIG.4

June 25, 1957 J. GRATZMULLER 2,796,769

CRANK-SHAFT AND THE CORRESPONDING CRANK-CASE Filed Feb. 3. 1954 3Sheets-Sheet 3 h ll/ r0 3 L s \l lls III I b r [-M'dj CRANK-SHAFT ANDTHE CORRESPONDING CRANK-CASE Jean Louis Gratzmuller, Paris, FranceApplication February 3, 1954, Serial No. 408,009

Claims priority, application France February 5, 1953 6 Claims. (Cl.74-49) The present invention relates to reciprocating machines of thetype comprising a crank-'s'haftmounted in a crankcase and areciprocating member operatively connected with said crank-shaft.

In the existing machines of this type, the shaft is journalled in saidcrank-case by means of separate bearing structures provided withanti-frictionmeans such as balls, rollers, needles, brass linings,graphite linings, etc. Said bearing structures have to .be properlymounted in corresponding bores provided in the crank-case walls, thejournal surfaces of the shaft being, in turn, so adjusted as to fitproperly in said bearing structures.

It is obvious that such a way of mounting the shaft is time and workconsuming .and, .hence, costly.

The present invention has for .its purpose to simplify the mounting ofthe shaft in its crank-case without impairing the desired alignment ofthe shaft and even improving the same.

The present invention permits such .a simplification of the mounting ofthe crank-shaft in the crank-case by completely eliminating theintermediate bearing structures and by having recourse to the naturalproperties .of different metals to obtain ultimately a directjournalling of the crank-shaft in the crank-case walls.

It is an object of the invention to make the crank-case or, at least,the part of the same which has to receive the crank-shaft, of a metalhaving ahigh coefficient of thermal expansion and to journal thecrank-shaft made of a metal having a lower coeflicient of thermalexpansion directly in opposite walls of said crank-case.

This direct .journalling of a crank-shaft in the Walls of a crank-casepermits machining the two journals of said shaft on a lathe withoutremoving the workpiece from said lathe, which naturally permits anabsolute axial alignmentof the two journals and also the boring of thetwo bearing surfaces provided in two opposite walls of the crank-case ona lathe, equally without removing the workpiece from said lathe.

It is to be understood that by having such perfectly aligned journalsand bearing surfaces, it becomes easy to put the crank-shaft in place inits crank-case without any adjustment whatsoever. It even permits anonselective assembly between crank-shafts and crank-cases, which meansthat a series of standardized crank-shafts and a series of correspondingstandardized crank-cases can be interchangeably assembled betweenthemselves.

Another object of the invention is .to make the crankcase, .or at leastthe part of the same receiving the shaft, in an aluminium alloy and tomake the shaft in steel. Experience has shown that this particularcombination of metals gives excellent results. In fact, if the fitbetween .the journals .of the shaft and the bearing surfaces of thecrank-case walls is too tight, the rotation of the shaft developsfriction and, hence, heating of the parts, the high coefficient .ofexpansion of the metal forming the crank-case walls resulting indifferential expansion, thus automatically reducingfriction and limitingheating.

Another object of the invention is to give to one of the States Paterjournals of the crank-shaft and the corresponding bearing surface boredin a wall of the crank-case a greater diameter than those of the otherjournals of the crank-shaft and, hence, the other bearing surfacesintended to cooperate with said journals, which permits installing thecrank-shaft by an axial displacement of the same, said crank-shaft beingintroduced in the crank-case with its smaller journal ahead.

A more particular object of the invention is to give to the smallerbearing surface .bored in a wall of the crank-case the shape of an axialthrust bearing, which permits holding the crank-shaft in place aftermounting, as described above, by mere locking of :its end opposite tothat which is journalled in said axial thrust bearing.

A still more particular .object 'of the invention is to provide acrank-shaft designed and journalled in the manner described comprising,at .oneend, a journal the crosssection of Which is comprised within thatof an excentered mid-portion which is to be used as an eccentric sheaveto be operatively connected with the reciprocating member of themachine, the cross-section of said eccentric sheave being, in turn,comprised within that of the other journal of the crank-shaft, the largeend of the crank-shaft passing throughthecorresponding casing wall andbeing provided with an external extension adapted to receive suitabledriving means.

A still more particular object of the invention is to combine thecrank-shaft-crank-case combination just described with a connectingmember :of the type described in co-pending application Ser. No.408,008, filed February .3, 1954, by same applicant for Crank Pin-PistonConnecting Means interposed between said eccentric sheave and .areciprocating member.

A still more particular .object of the invention is to combine such a.crank-shaft-crank-case combination and such connecting member with theplunger piston of a hydraulic pump of the type described in co-pendingapplications Ser. Nos. 408,006 and 408,007 filed February 3, 1954, bysame applicant for Hydraulic Pumps and Improvements in Hydraulic PumpingUnits, respectively. I

A further object of the invention .is to provide in acrank-shaft-crank-case combination of the type described particularlysimple and eflicient lubricating means fed from the crank-case oil sumpfrom which oil isconducted to the bearings to pass therethrough,whereafter it is returned by gravity to said sump for re-distr'ibutionthrough said lubricating means.

Other objects and advantages of the invention 'will be apparent from thefollowing detailed description together with the accompanying drawingssubmitted for purposes of illustration only and not intended to definethe scope of the invention, reference being bad, for this purpose, tothe subjoined claims.

In these drawings:

Fig. l is a sectional view of 'a hydraulic pump provided with acrank-shaft and a crank-case according to the invention.

Fig. 1a is a detail vertical section taken .on the line la-a of Fig. l.

Fig. 2 is a partly elevational; partly cross-sectional view along axisXXof-Fig. 1.

Fig. 3 is a partly axial sectional View showing .an alternativeembodiment of the pump sbarrel.

Fig. 4 is an exploded view of the crank-shaft according to the inventionand adevieeito interconnect the same with a plunger piston, or thelike.

Referring to the drawings, and more particularly to the cylinder of thepump, a member 4 in which is formed the intake valve, a member 5 in whchis formed a delivery valve and a plug member 6, which, in the exampleshown, is screwed, in the threaded. end of barrel 2 and holds in placethe whole assembly of the above described members, suitable packingrings such as 7, 8 and 9 being interposed between the relevant membersof the stack.

It is to be noted that the packing rings 8 and 9 ensure tightness bothbetween members 3 and 4 and members 5 and 6, respectively, and betweensaid members and the inner wall of barrel 2. Members 3, l, 5 and 6 arepreferably made of a metal having the same coeflicient of thermalexpansion as barrel 2, so as to avoid any leakage or destruction of thepacking rings, as the temperature of the pump varies in operation.

10a is the inlet of the pump to which the liquid is fed through asuitable pipe 10b. 11 is the outlet provided through plug 6. The intakevalve essentially comprises a ball 51 cooperating with a seat 12 andguided and centered by a tubular extension 13 of member 4. The liquid issucked into the pump through inlet 10a, a passage 14 and lateral holes16 drilled through the wall of the tubular extension 13 in the nearvicinity of seat 12.

The delivery valve which is formed in member 5 comprises a ball 17cooperating with a seat 18. This last valve, of a more conventionaltype, offers between ball 17 and its cylindrical housing, suflicientannular clearance to permit flowing of the liquid towards outlet 11.Both valves are provided with abutment means to limit the lifting strokeof their respective ball, said abutment means being each constituted bya gudgeon pin 19.

It is to be noted that the delivery valve is located directly above 'theintake valve, said valves being both so designed that the air whichcould be accumulated in the pump cylinder before the pump is startedwill tend naturally to escape through outlet 11.

A complete separation is provided between barrel 2 andcrank-case 1, saidseparation being ensured by an 7 to establish a permanent communicationthrough at least one passage 24 with an annular chamber 23 constantlycommunicating in turn through a fitting 25 and an individual pipe(connected to said fitting 25) with the above mentioned liquid tank.

The long piston part extending between the pump chamber and the portion22 of reduced diameter already ensures a good tightness. However,leakages can still occur, particularly when the pump delivers liquidunder a very high pressure.

It will be readily understood that these leakages will return to theliquid tank through the free communication offered by the abovementioned individual pipe rather than forcing their way between thelower part of the piston and cylinder towards the crank-case 1.

Another important advantage of maintaining the annular space 52 inpermanent and free communication with said liquid tank is to ensure insaid space a constant liquid pressure slightly superior to the pressurein the crankcase 1. Due to this liquid pressure seal, air cannot besucked into the pump chamber during the suction stroke.

Still another advantage of the complete separation between barrel 2 andcrank-case 1 is that of permitting the use in the latter of any desiredlubricant, whatever the nature of the liquid delivered by the pumpingunit.

As shown in Fig. 3, it is possible, in certain cases, to avoid the abovementioned individual pipe and to establish a permanent communicationbetween the annular chamber 23 and, hence, the annular space 52 and aspace upstream of the intake valve, the inlet port 14 of which is at thesame pressure as the feeding tank, by means of passages 26. Thissimplified arrangement may be adopted, in particular, when the feedingtank is located in the near vicinity of the pump, so that noobjectionable loss of pressure is to be feared.

On the contrary, when such losses of pressure could happen in the mainfeeding pipe 10b, e. g. in the case when the feeding tank is located ata considerable distance rom the pump, it will be preferred to adopt theembodiment described with reference to Figs. 1 and 2 in which thepresence of the independent duct 58 through which no forced circulationof liquid takes place maintains with safety in the annular space 52 theslight above mentioned over-pressure.

Referring again to Figs. 1 and 2, piston 21 is reciprocated by means ofan eccentric sheave 28 integral with a crank-shaft A.

According to the invention, crank-shaft A is journalled into cylindricalbearing surfaces 29 and 30 directly bored in two opposed walls ofcrank-case 1.

In the example shown, according to another feature of the invention,said walls are relatively thin to ensure a certain flexibility, but theyare provided with two integral embossings and 116 which ensure to thebearing surfaces 29 and 30 the desired axial length.

Said crank-case is made of a metal having a high coefficient of thermalexpansion and a low modulus of elasticity, such as an aluminium alloy.Thanks. to this atrangement, it is possible to journal shaft A directlyin the above described bearing surfaces bored in crank-case 1 withoutany risk of jamming.

Thus, a certain flexibility of the crank-case walls and the highcoeflicient of thermal expansion of the metal of said walls ensure agood operation of the pump without providing any special hearings tojournal shaft A.

As shown in Fig. 4, crank-shaft A is connected with the plunger piston21 of the pump through connecting member 27, which in the example shownhas the shape of a disc. 7

Two parallel bores 28a and 32 are formed in body 27. T he first one 28ahas for its purpose to ensure ournalling of body 27 around the eccentricsheave 28 of crank-shaft A. In the second bore 32 is freely engaged apivot pin 31, the axis of which constitutes the usual axis ofarticulation of the body 27, which acts as a connecting rod, on piston21.

The piston 21 is itself articulated to said pivot pin 31, saidarticulation ensuring the second degree of freedom to be provided by theconnecting member according to the invention and proper to take care ofpossible disalignment between piston 21 and crank-shaft A. Pivot-pin 31is provided for this purpose with a hole 31a into which is engaged theend of piston 21. Thisend, before being engaged in said hole 31a passesthrough a slot 27a formed in the mid-plane of the disc 27, the width ofsaid slot being greater than the diameter of the piston 21. Thearticulation of the piston 21 in the hole 31a of the pivot pin 32 isensured by a cylindrical gudgeon-pin 33 which is engaged throughdiametral holes 33a drilled through the pivot pin 31 and a correspondinghole 33b drilled in the end of piston 21. The diameter of the hole 31ais also greater than the diameter of the piston 21, to permit thepivoting of the same.

It will be readily understood that the assembling of the parts of'such aconnecting device is practically instantaneous, the operations ofassembling consisting simply in introducing pivot pin 31 in the bore 32,then engaging the end of piston 21 in the hole 31a through the slot 27aand, finally, driving in the holes 33a, 33b and 33a the gudgeon pin 33.a

The shape of the slot 27a and its location, are such that, when thepivot pin 31 with the end of piston 21 engaged therein .is brought in anangular position in whichsaid piston abuts against .one end of saidslot, one

of the holes 33a is apparent near the other end of said slot, so thatthe gudgeon-pin 33 can be easily engaged in the three correspondingholes 33a, 33b, 33a. In this position of the pivot pin 31, these threeholes are brought into alignment with a hole 34 drilled in the disc 27from the periphery of the same and which does not intersect bore 28a, sothat it does not interrupt the bearing surface of the latter.

It will be easily understood that :in this position of piston 21, :thegudgeon .pin .33 can .be easily removed through said hole 34 .to ensuredismantling of the whole assembly.

However, since in said extreme angular position of piston 21, hole 33ais in the immediate vicinity of the terminal edge of slot 27a, as soonas piston 21 leaves said terminal angular position, the gudgeon-pin 33will be imprisoned inside body 27. In particular, this is the case whenthe connecting member according to the invention is mounted between theeccentric sheave 27 of crank-shaft A and piston 21, when said imprisonedgudgeon pin 33 will ensure interlocking of all parts of the drivingassembly thus obtained.

In the example shown in the drawings (see Fig. l), as already mentionedabove, the bearing surfaces 29 and 30 for shaft A have differentdiameters, while shaft A proper offers an end 35 of reduced diameteradapted to be journalled in bearing surface 29, the eccentric sheave 28of greater diameter and, finally, a portion 36 of still greater diameteradapted to be journalled in the bearing surface 30 of the crank-case 1.

Moreover, the circumference defining the cross-section of journal 35 iscomprised within that which defines the cross-section of the eccentricsheave 28, while the latter is, in turn, comprised within thecircumference which defines the cross-section of journal 36. Thisarrangement permits mounting the shaft A by introducing the same Withits reduced end 35 ahead, first into the bearing surface 30, thenthrough the bore 28a of the disc 27 and, finally, into the bearingsurface 29. Once shaft A is mounted as just described, it is secured bymeans of a plug 38 provided with a hole through which passes the end 37of shaft A on which a suitable driving member, such as a pulley 39, iskeyed.

It is a particular feature of the invention to combine the improveddirect crank-shaft mounting in the crankcase walls with connecting meansbetween the crankshaft and the reciprocating member as just described,due to the fact the perfect alignment of the crank-shaft by machining inone lathe operation of both bearing surfaces of the crank-case walls andalso in one lathe operation of the crank-shaft journals can be obtainedwithout taking care of precise right angularity between the shaft andthe reciprocating member. This combination permits, in fact, mountingthe pump barrel 2 on the crank-case 1 by screwing said barrel into athreaded hole of a plate 20, the same being secured on the crank-case 1by means of stud-bolts 123.

In the example shown, in order to facilitate the assembling, the bottomof the crank-case, forming the sump 113, is constituted by a separatepiece 1a assembled with the crank-case proper 1 by bolts 110 withinterposition of a packing washer 114. The lubricating oil is introducedin the sump 113 through a passage 111 provided with a plug 112. Thispassage 111 is so arranged as to permit observing the oil level in thesump.

The lubrication of shaft A is ensured from the sump 113 by rings 40-40afreely suspended on shaft A and prevented from escaping by a piano wire41 held in place by studs 124.

Rings 40 and 400, the lower end of which is immersed in the oilcontained in sump 113, are continuously rotated by friction under theirown weight on shaft A. Thus, they continuously raise oil from the sumpand bring it above the shaft A. Now, the internal walls of the crankcase1 are provided, in registration with the vertical di- .ametral plane of:the shaft, withvertical grooves 40b (see Figs. 1 and la) which collectoil from rings 40 .and 40a and direct said oil into the annularclearances provided between the bearing surfaces 29 and 30 and thecorresponding crank-shaft journals 35 and 3.6. The oil flows axiallybetween the bearing surfaces and the corresponding journals and ,iscontinuously returned to the sump through the passages 42 and 43.

At the smaller end of shaft A, journalled in embossing 115, which isformed as an axial-thrust bearing to provide lubrication of the very endof shaft A, the latter is provided with a portion-of reduced diameter118.

At the opposite, larger, .end of shaft A, there is 'provided aturbine-like .device .to :prevent .oil from leaking out crank-shaft A.The .frustro-conical rotating member 44 of said device is integral withshaft A, while its stationary member is constituted by a plug 38 tightlysecured on the outer end of embossing 116 by means of screws 119 andwhich comprises an inner skirt 120 which has for its function to preventoil from leaking around the reduced end 37 of shaft A and with an outerskirt 121 which has for its function to hold shaft A in place bycooperating with an abutment shouldering 117 provided on said shaft. Theannular groove 45 comprised between both skirts 120 and 121 of plug 38collects oil projected by the rotating member 44. A hole 122 is providedthrough the lower wall of skirt 121 to permit oil from the annularcollecting groove 45 to return into sump 113 through the above-mentionedoblique passage 43.

While the invention has been described with particular reference to apreferred embodiment, it is not intended to limit the scope of theinvention to the embodiment illustrated, nor otherwise than by the termsof the subjoined claims.

What is claimed is:

1. A casing structure for supporting a metallic rotary shaft, comprisinga main section, two coaxial cylindrical bearings for said shaft eachformed integral with one of two opposite side Walls of said mainsection, said main section being made of a metal having a greatercoeflicient of expansion than that of the metal of which said shaft ismade whereby frictional heat due to a tight fit of said shaft in saidbearings will cause greater expansion of said main section than of saidshaft so as to create clearance spaces between said shaft and saidbearings, and mechanical means to circulate lubricant through saidclearance spaces.

2. In a reciprocating mechanism, a crank-case comprising two oppositewalls made of a metal having a high coefficient of thermal expansion, acrankshaft made of a metal having a lower coefficient of thermalexpansion and having inner and outer end portions, twoaxially alignedbores of different diameter provided each in one of said opposite wallsto constitute bearing surfaces for said crankshaft, the diameter of thelarger bore being at least equal to the diameter of the circumference described by the crank of said shaft when the latter is rotating, and twojournals of different diameter on said crankshaft, each journal fittingin a corresponding bore and the journal of smaller diameter being formedon said inner end portion of said shaft, the arrangement being such thatsaid crankshaft may be introduced in said casing and journaled in saidbores by passing its inner end portion axially through the bore oflarger diameter.

3. A crankshaft-crank-case assembly according to claim 2, in which saidwalls are each formed with an integral embossing, said bearing surfacebeing bored in said embossings.

4. A crankshaft-crank-case assembly according to claim 3, in which theembossing which receives the journal of smaller diameter also forms anaxial thrust bearing for said crankshaft.

5. A casing for a horizontal metallic rotary shaft having two oppositejournal-forming end portions of different diameter and an eccentric orcam intermediate said end portions, comprising a socket formed integralwith one of two opposite sidewalls of said casing and a, boss formedintegral with the other of said two opposite side walls, said casingbeing made of a metal having a greater coefficient of expansion thanthat of the metal of which said shaft is made, a cylindrical blind borein said socket constituting a bearing surface for the end portion ofsmaller diameter of the shaft, a cylindrical bore in said boss coaxialwith said blind bore and constituting a bearing surface for the endportion of larger diameter of said shaft, the diameter of saidcylindrical bore being at least equal to the diameter of thecircumference described by said eccentric or cam as said shaft isrotated, and means associated with said boss to hold said shaft againstlongitudinal displacement.

Referencs'Cited in the file of this patent QLUNITED STATES PATENTS1,456,082 .Warren May 22, 1923 1,807,725 Brackman June 2, 1931 1,847,418Steedrnan Mar. 1, 1932 2,039,469 Williams May 5, 1936 2,398,364Elfstrom' Apr. 16, 1946 2,426,940 McCullough Sept. 2, 1947 2,648,573Wheildon Aug. 11, 1953 OTHER REFERENCES American Machinist, page 153,Iune'5, 1947.

